1. Field of the Invention
The present invention relates to a drain separator for separating a gas component and a liquid component from a mixture fluid containing a gas and a liquid.
2. Description of the Related Art
A gas/liquid separator (drain separator) has been hitherto known, in which, for example, a separator is applied to a steam-generating unit for generating steam containing water so that the gas-water mixture fluid generated by the steam-generating unit is separated into a gas component (steam) and a liquid component (water).
In the case of a steam-generating unit 2 shown in FIG. 6 to which a gas/liquid separator is applied, a revolving vane 4, which has a plurality of blades, is provided rotatably in a cylindrical gas-water ascending tube 3. A cylindrical water-falling barrel 5 is provided to cover the gas-water ascending tube 3 around the gas-water ascending tube 3. A space 6 is formed between the water-falling barrel 5 and the gas-water ascending tube 3. Further, a discharge port 7 for discharging separated water is formed on the lower side of the water-falling barrel 5.
When the gas-water mixture fluid is allowed to flow from the lower side to the upper side along the gas-water ascending tube 3, then the revolving vane 4 is rotated by a predetermined amount depending on the flow rate or the flow velocity of the gas-water mixture fluid, generating the swirl flow in the gas-water mixture fluid. Accordingly, the gas-water mixture fluid is separated into the steam and the water under the centrifuging action. The steam component is further moved upwardly from the gas-water ascending tube 3 to flow into an internal cylinder 9 via a cylindrical orifice 8. Hot water is pressed against the gas-water ascending tube 3, and flows downwardly via the space 6. Then, the hot water is returned to a water feed section of the steam-generating unit 2 via the discharge port 7 (see, for example, Japanese Laid-Open Patent Publication No. 11-141802).
The gas/liquid separator 1 is constructed such that the revolving vane 4 is rotated under the gas-water mixture fluid flowing through the gas-water ascending tube 3. Therefore, when the flow velocity or the flow rate of the gas-water mixture fluid is small, rotation of the revolving vane 4 is reduced, failing to rotate the revolving vane 4 desirably. Therefore, it is difficult to centrifuge steam and water contained in the gas-water mixture fluid under the rotating action of the revolving vane 4.
The following countermeasure is assumed to reliably separate the gas-water mixture fluid even when the flow rate or the flow velocity of the gas-water mixture fluid is small as described above. That is, for example, a gas/liquid separator, in which a driving source is provided to urge the rotational force on the revolving vane 4, is capable of separating the gas-water mixture fluid with the revolving vane 4 driven by the driving source.
As shown in FIG. 7, such a gas/liquid separator 10 includes an electric motor 12 arranged under a casing 11. A rotor 14, which is connected to a rotary shaft 13 of the electric motor 12, is rotated under the driving action of the electric motor 12. An internal fin 15 is provided in the rotor 14. A liquid discharge flow passage 16, through which the liquid separated from the gas-liquid mixture gas is to be discharged, is formed on the outer circumferential side of the internal fin 15. The rotor 14 has a gas-permeating film 18, through which only the gas is permeable, provided for a gas discharge passage 17 open toward the inner wall surface of the casing 11.
When the gas-liquid mixture gas is introduced from an inflow port tube 19 installed in the casing 11, and the electric motor 12 is driven, making the gas-liquid mixture gas flow while swirling in the casing 11 under the rotary action of the rotor 14, thereby centrifuging gas and liquid. The gas is discharged via the gas-permeating film 18 to the outside from a gas outlet tube 20 of the casing 11. The separated liquid flows radially outwardly in accordance with the centrifugal force, and then discharged via the liquid discharge flow passage 16 to the outside of the casing 11 (see, for example, Japanese Laid-Open Patent Publication No. 2003-80114).
In the case of the conventional technique concerning Japanese Laid-Open Patent Publication No. 2003-80114, the internal fin 15 and the liquid discharge flow passage 16 are integrally provided for the rotor 14 connected to the electric motor 12. Therefore, the electric motor 12 for rotating the rotor 14 may be large-sized, and the structure of the rotor 14 may be complicated, inadvantegeously.
Further, because the shape of the liquid discharge flow passage 16 is complicated, when the liquid separated from the gas-liquid mixture gas flows, clog-up tends to occur due to the dust or the like contained in the liquid. Further, when the clog-up occurs, the separation efficiency of the gas-liquid mixture gas is lowered.